Hantavirus pulmonary syndrome: A severe lung condition caused by hantavirus infection. Abbreviated HPS. In 1993, HPS struck the Four Corners area (where the states of Arizona, New Mexico, Nevada, and Utah meet) with devastating, frequently fatal consequences. As the name indicates, HPS is due to a hantavirus. The HPS outbreak in Four Corners followed 2 years of more rain, more foliage, and more deer mice than usual.